Cable data systems are used to allow cable TV subscribers use the Hybrid-Fiber-Coax network as a communication link between their home networks and the Internet. As a result, computer information (Internet Protocol packets) can be transmitted across the Hybrid-Fiber-Coax network between home computers and the Internet. The Data Over Cable Service Interface Specification (“DOCSIS”)—defined by CableLabs®—specifies the set of protocols that must be used to effect a data transfer across the Hybrid-Fiber-Coax network (“HFC”). Two fundamental pieces of equipment facilitate this data transfer: a cable modem (“CM”) which is positioned in the subscriber's home, and a Cable Modem Termination System (“CMTS”) which is positioned in the head end of the cable TV company.
In addition to data traffic, subscribers are more and more obtaining telephony voice services over networks other than the traditional public switched telephony network (“PSTN”). A multiple services operator (“MSO”) may provide such telephony services, in addition to data over cable service via DOCSIS. For example, CableLabs has established the PacketCable™ standard for providing telephony services over cable. A subscriber typically has a device that includes a DOCSIS cable modem for transmitting and receiving data and a media terminal adaptor (“MTA”), or embedded MTA (“eMTA”) for processing voice traffic for transmission and reception over cable.
Subscribers are also receiving video content from their traditional cable television service provider that is delivered digitally instead of as an analog signal. For example, a typical 6 MHz (in United States) channel that carries a single analog video signal may carry multiple video content programs in a digital format. Moreover, the digital video content signals may be delivered according to Internet Protocol, which is known in the art. To facilitate the delivery of digital video to a subscriber, a DOCSIS set-top gateway device (“DSG”) may be used, as described in “DOCSIS Set-top Gateway (DSG) Interface Specification,” having application Ser. No. 11/808,510, which is Copyrighted 2001-2005 Cable Television Laboratories, Inc., (hereinafter referred to as the “DSG specification”) and is incorporated herein by reference in its entirety.
Among other aspects, the DSG specification defines a one-way mode of operation and a two-way mode of operation. The two-way mode facilitates interactive out-of-band communications between Set-top Controller and the Set-top Device. If the Set-top device cannot send data in the upstream direction, the device goes into the degraded one-way mode and cannot continue interactive communication with the controller. Although there are error conditions that can cause the Set-top Device to go into one-way mode which the device has no control over, there are also scenarios where the DSG Client Controller directs the DSG's embedded cable modem (“eCM”) to go into one-way mode. For example, the client controller may decide that it needs to ‘listen’ to a DSG tunnel on a different downstream channel, either because the original tunnel no longer applies to the embedded set-top box (“eSTB”), or the eSTB has multiple DSG clients that need access to different tunnels.
As a result, the eCM needs to tune to a new channel, and while the eCM registers on the new channel, the Set-top device will either have no communication or will be in one-way mode—in other words in a degraded mode. Since one or more users that are using the set-top box device may need uninterrupted upstream capability, there is a need in the art for a method and system that minimizes this amount of time a set-top box device operates in degraded mode when the degradation is due to actions under the DSG Client Controller's control.